1. Selikoff, I. J., Hammond, E. C. & Churg, J. J. Am. med. Ass. 204, 104–110 (1968).
2. Hammond, E. C. & Selikoff, I. J. Int. Agency Res. Cancer Sci. Publ. 8, 312–317 (1973).
3. Birks, J. B. & Cameron, J. W. Proc. R. Soc. A 249, 297–317 (1959).
4. Brunauer, S., Emmet, P. H. & Teller, E. J. Am. chem. Soc. 60, 309–319 (1938).
5. Timbrell, V. Proc. Int. Pneumoconiosis Conf., Johannesburg, 1969. 28–36 (Oxford University Press, 1970).